1. Field of the Invention
This invention relates to recirculating roller bearing assemblies, and more particularly to a linear motion recirculating roller bearing assembly of the type including a plurality of rollers which are contained in a track for rolling recirculating movement along parallel, spaced apart, load bearing and return paths.
2. Description of the Related Art
Linear motion recirculating roller bearing assemblies having multiple tracks for longitudinal movement along a shaft are known in the art. See, for example, U.S. Pat. Nos. 4,181,375, 4,293,166 and 4,463,992. These bearing assemblies are typically characterized by a housing which forms a plurality of tracks arranged in radial planes with respect to the longitudinal axis of the shaft. Each of the tracks has a load-bearing path wherein the roller elements contact the shaft and a spaced return path for serially recirculating the roller elements back to the load-bearing path. Turnarounds are positioned at each axial end of the tracks to interconnect the load-bearing and return paths. These bearing assemblies, particularly the assembly shown in the '922 patent, are difficult to manufacture because the load bearing surfaces must be ground in a longitudinal arcuate configuration to accommodate the rollers. This feature also makes it difficult for the bearing assembly to take load over the whole roller.
A plurality of individual axial guides are commonly provided in conjunction with the load bearing paths to guide and separate the rolling elements in the load bearing paths. These axial guides are usually in the form of separate axially extending elements which are individually placed between the end caps at the axial ends of the bearing assembly. Similarly, a plurality of individual inner guides may be positioned at each of the inner axes of the turnarounds to guide the roller elements from the load-bearing tracks to the return tracks. Both the axial guides and the inner guides usually must be individually and separately positioned within the bearing assembly. This technique is both time consuming and inefficient.
In addition to the problems associated with assembling and positioning the axial and inner guides, bearing assemblies making use of typical individual bearing plates tend to have alignment and positioning problems associated therewith. These bearing plates are usually positioned longitudinally over the load bearing tracks and serve to transmit loads from the carriage, through the roller elements, to the shaft. If these bearing plates are not properly and securely positioned, the bearing assembly will not operate efficiently and may cause binding and/or misalignment of the roller elements.
Load-bearing plates with a portion of the return paths integrally formed therein have been designed for use in chain-type bearings. See, for example, U.S. Pat. No. 4,790,671. These bearings, however, are not designed for use on round or near round shafts nor are they intended to be used as a subassembly in side-by-side radial arrangement for roller bearings used with round or near round shafts.
Therefore, it is highly desirable to have a high load capacity bearing assembly made up of a plurality of bearing plates interfitting in an annular configuration for linear motion along a round or near round shaft. Similarly, it is highly desirable to have a high load capacity bearing assembly which provides an integral axial and inner guide assembly for efficient and consistent positioning within the assembly while properly and securely aligning the bearing plates.
Accordingly, it is an object of the present invention to provide a linear motion roller bearing assembly for operation on a substantially cylindrical shaft which bearing has a high load capacity.
It is another object of the present invention to provide a linear motion roller bearing assembly incorporating annularly arranged bearing plates for linear motion along a round or near round shaft.
It is another object of the present invention to provide a linear motion roller bearing assembly incorporating integral axial and inner guides for ease of alignment and fabrication.
It is another object of the present invention to provide a linear motion roller bearing assembly having integral axial and inner guides which align and secure bearing plates within the assembly.
These and other highly desirable and unusual results are accomplished by the present invention in a linear motion roller bearing assembly comprising a plurality of annularly arranged bearing plates having at least a portion of load bearing and return paths formed therein. The bearing assembly may further comprise axial and inner guides integrally formed and adapted to secure and align a plurality of bearing plates therein for use on a substantially cylindrical shaft.
Objects and advantages of the invention are set forth in part herein and in part will be obvious therefrom or may be learned by practice with the invention, which is realized and attained by means of instrumentalities and combinations pointed out in the appended claims. The invention comprises the novel parts, constructions, arrangements, combinations, steps and improvements herein shown and described.